Disc drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g., air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each head gimbal assembly. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a compliant connection that allows the slider to pitch and roll and assume an orientation relative to the disc that balances the hydrodynamic forces that support the slider.
The slider includes a bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to lift and fly above or in close proximity to the disc surface.
As recording density on discs increases, recording heads fly closer to the disc surface to maintain resolution between adjacent data tracks. Thus, the physical separation between the slider and the disc surface at the recording head is an important parameter to disc drive performance. Prior art sliders provide a focused pressure peak on the slider substrate near the transducer region to minimize variation of the physical separation, or “fly height.” Other systems use active or passive fly height control mechanisms to minimize variation. During operation of the drive, however, elements near the trailing edge of the slider can experience recession due in part to thermal or manufacturing effects that disrupt the overall performance of the disc drive. These elements can include a basecoat layer, overcoat layer, transducer pole tips and substrate features. If the basecoat layer, overcoat layer, and pole tips become recessed relative to the air bearing surface features of the slider, the effective fly height at the pole tips will increase, causing degradation in read/write performance. Additionally, manufacturing variations in the shape of the slider and the geometry of the bearing surfaces may effect fly height and fly height modulation.
A disc head slider is therefore desired that reduces sensitivity of the fly height and fly height modulation to manufacturing variations and recession of elements on the slider. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.